Ellipsograph



July 2-8, 1953" J. c. COATS 2,546,623

ELLIPSOGRAPH Filed May 1. 1951 I 3 Sheets-Sheet l JNVENTOR. Jsse C.Coats July 28, 1953 J. c. COATS 2,646,623

ELLIPSOGRAPH 7 Filed May 1, 1951 5 Sheets-Sheet 2 IN VEN TOR.

Jsse C. COGZS M 411% y 8; 1953 J. c. COATS 2,646,623

ELLIPSOGRAPH Filed May 1, 1951 3 Sheets-Sheet 3 fig 6 1 'vi 1 /a m 1INVENTOR.

6 a. HQ Jsse C. Coais L Patented July 28, 1953 V UNITED STATES PATENTOFFICE Jesse C. Coats, Pocatello, Idaho Application May 1,1951, SerialNo. 223,918

My invention relates to improvements in an ellipsog-raph.

It is the principal purpose of the present invention to provide anellipsograph in which the moving parts of the device are all carried ona triangular plate in such a fashion that it is a simple matter to setthe ellipsograph in position with respect to the major and minor axesand thereafter draw the ellipse of the proper size. I am aware thatthere have been a number of prior devices patented for the purpose ofmaking curved figures such as ellipses. The present device however, isparticularly novel in the parts construction whereby an ellipse of anextremely small size can be drawn with an instrument which also willmake quite largefigures.

My invention is embodied in an ellipsograph which utilizes a triangularbase plate with two slots, one extending parallel to the base side ofthe triangle and the other extending perpendicular to the base side ofthe triangle. The base 2 Claims. (01. 33-31)" plate has two guide pointmounting arms offset outwardly from the base edge of the triangle and athird guide point in line with the slot that is perpendicular to thebase edge of the triangle The scribing arm is laterally offset from theline which passes through the pivotal connections to the minor axisguide and the pivotal axis of the scribing arm. This construction leavesthe major 7 description are illustrative only and are not intended tolimit the invention except insofar as it is limited by the claims.

In the drawings:

Figure 1 is a perspective view showing the ellipsograph as it ispositioned on a sheet having the major and minor axes marked thereon;

V Figure 2 is an enlarged side'view showing the guides and the scribingtool as they appear when brought into position to align the pivotalconnections of the scribing arm and the scribing tool vertically withrespect to theplane of the sheet; Figure 3 is a plan view of theellipsograph showing the scribing arm positioned at the beginning of thedrawing operation with the scribing tool on the major axis;

Figure 4 is a sectional view on the line 44 of Figure 2;

Figure 5 is a view in side elevation of the ellipsograph looking atFigure 3 from the left side;

Figured is a perspective view of the tool holder that mounts thescribing-tool;

Figure"? is a bottom view of the ellipsograph by screws 20 and 2|.

2 with a portion of the triangular base broke away; and

Figure 8 is an enlargedfragmentary sectional view taken on the line 8-8of Figure 3.

Referring now in detail to the drawings, my

improved ellipsograph comprises a plate H] of' sheet metal or the like.The plate is in the form of an isosceles triangle with one side, markedHla, being the base side of the triangle. A guide way slot ll extendsparallel to the base side of The plate It) is supported by three needlepoint Y supportsl3, l4 and 5.15." The support I 3 is on a line bisectingthe triangular plate l0. The supports I4 and I5 are mounted onprojecting arms l5 and Il-which project equal distances beyond the baseside 10a of the triangle. A guide runner IS inthe form of a rectangularblock has'a reduced portion 18a seated inthe guide way [2.

A plate I9 is secured to the reduced portion [8a The guide runner l8 hasa projecting arm 22 parallel to the guide way [2. The arm 22 providesthe pivot fora'scribing or drawing arm 23. The arm-22 is spaced abovethe plate lfl for a purpose which will presently appear. A shoulderedscrew 24 is the pivot member connectingthe arms 22' and 23.

It will be noted that the arm 23 has a raised The runner 26 has areduced portio'nll in the guide way II. A plate 28 is secured to thereduced portion 21 by'two screws 29 and 36. 'The' runner 26 has alaterally extending arm 26a to which the bar 25 is pivoted by apivot'member 3 I. The bar 25 is slotted so that the arm 23 slidesthrough it. -A set screw 32 is utilized to lock the bar 25 at thedesired position on the arm. 23.

'A tool holder 33 is also slotted to receive the arm 23 and is securedthereon by a set screw 34. This tool holder has a downwardly andlaterally offset tool mounting portion 35 which has means for securing ascribing tool 36 in position. The scribing tool 36 maybe a pencil. penor other suitable marking device. "A set screw 31 secures the scribingtool in place;

The way in which the ellipsograph is used may bev briefly described asfollows:

After themajoraxis and minor axis lines of the minor axis.

of the axes are marked off on the drawn axis lines, the ellipsograph isplaced on the drawing in such a manner as to cause the needle pointsupport 13 to rest on the minor axis line. The set screw as on the toolholder 33 is then loosened and the arm 23 is swung to a positionparallel to the major axis line. moved along the arm 23 until thescribing tool 35 lies directly over the mark drawn on the major axisline to denote the length of the major axis. The set screw 34 on thetool holder is then tightened to prevent further movement of the toolholder 33 along the drawing arm 23.

the minor axis line. This position will be indicated when the scribingtool 36 lies directly over the extended minor axis. The set screw 32 onthe minor axis adjustment bar 25 is then loosened and the arm 23 ismoved endwise until the scribing tool rests directly on the mark drawnon the minor axis line to indicate the length of The set screw 32 on theminor axis adjustment bar 25 is then tightened to prevent any furthermovement of the arm 23 through the bar 25.

The adjustments having been made as described above, the arm 23 is againswung to bring the scribing tool 36 directly over the mark on the majoraxis line that indicates the length of the major axis. The scribing tool36 is then lowered and the arm 23 is swung through its full travel todraw one half of the ellipse. In order to draw the opposite half of theellipse, theplate I is lifted and turned around so that the needle pointsupport 14 seats in the hole made by the needle point support l and theneedle point support l5 seats in the hole previously made by The toolholder 33 is The draw-' ing arm is then swung into position parallel tothe needle point support Hi. The arm 23 is i between the bar 25 and thearm 26a on the other hand can be brought completely into alignment ifdesired. When the pivots are aligned the arm 23 will move the scribingtool in a circle. Also the scribing tool 36 can be brought as close tothe center of the ellipse as necessary. As illustrated in Figure 2 andin Figure 4 of the drawings, the tool 36, the pivot screw 3| and thepivot screw 34 are axially aligned. This is made possible by theconstruction of the portion 23a and the ofiset part 35 of thetoolholder. The bar 25 and the arm 26a are of such length that their pivotalconnection lies in a plane vertical to the plate l0 through the pivotscrew 24 and the scribing tool 36. The offset portion 35 may be soconstructed as to make the tool point visible through or beneath it inorder to facilitate positioning of the tool point on the marksindicating the lengths of the major and minor axes. This may be done bymaking the offset portion 35 transparent. A suitable material such asglass or a transparent plastic composition can be used. The arm 23 doesnot obstruct the view of the major and minor axis lines because it isoffset by the portion 23a.

It is believed that the nature and advantages of my invention will beclear from the foregoing description. Having thus described myinvention, I claim:

1. An ellipsograph comprising a base plate having a long guide way and ashort guide way therein, the short guide way being perpendicularto thelong guide way on a line bisecting said long guide way, a needle pointsupport secured to said base on said line adjacent to the end of theshort guide way most remote from the long guide way, said base havingprojections adjacent to the ends of said long guide way, needle pointsupports at the free ends of said projections on a line parallel to saidlong guide way, a runner slidably mounted in the short guideway andhaving an arm thereon spaced above the plate, a scribing arm having a U-shaped end and a laterally offset portion on said end above the arm, apivot member connecting the oiiset portion to the arm on said runner, asecond runner slidably mounted in the long guide way and having an armextending over the plate, and over a straight line connecting said lastnamed needle point supports, a bar adjustably mounted on said scribingarm, a pivot member connecting said bar to said last named arm on anaxis intersecting the straight line between said last named needle pointsupports, and a scribing tool holder adjustably mounted on said scribingarm, said tool holder having a. tool holding socket located in a commonplane with said pivot members and offset laterally and downwardly fromthe scribing arm below the level of said bar.

2. In an ellipsograph, a base plate, three needle point supports forsaid base plate positioned at the corners of an isosceles triangle sothat the two supports at the base of the triangle may be set upon themajor axis line with the third support on the minor axis line of anellipse to be drawn, a runner slidably mounted on said base for movementparallel to a line connecting said two supports, a second runnerslidably mounted on said base for movement along a line through thethird support and perpendi'cular to the path of movement of the firstnamed runner, said second runner having a pivot thereon spaced above thebase plate, a scribing arm having a laterally offset, raised por tionconnected to the pivot of the second runner, a bar adjustable lengthwiseof said scribing arm and having a pivot connected to said first namedrunner, said last named pivot being spaced the same distance from thescribing arm as the first named pivot but below the level of thefirst'named pivot andabove the base plate so that the pivots may bemoved into vertical alignment, and a scribing tool holder adjustablelengthwise onsaid scribing arm, said tool holder having a tool mountingsocket ofiset laterally and downwardly with respect to the scribing armto lie in a common vertical plane with said pivots but below the levelsof said pivots.

JESSE C. COATS.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain Sept. 23, 1948

